The oldest organisms and are divided into two groups, the acheabacteria and the eubacteria. a) algae b) eukaryotes c) prokaryotes d) viruses

The correct answer is -

C)Prokaryotes.

Explanation:

Prokaryotes are the group of organisms that do not possess true nucleus and membrane bound subcellular organelles (unlike eukaryotes) such as bacteria.

These organisms are divided into two domains (according to three domain system of classification) that are acheabacteria (such as Methanogens) and the eubacteria (such as E.coli). They are the oldest group of organisms.

Thus, option C) is the right answer.

answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation:

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